This invention pertains to devices for measuring strain and, in particular, to a differential variable reluctance transducer and telemetry system for use in delicate or hard to reach areas.
There have been a number of attempts to develop highly accurate miniaturized sensors to be used by the medical profession and by industry to measure strains. Examples of this type device are many systems using Hall Effect displacement sensors. The U.S. Pat. No. 4,813,435 issued to Steven W. Arms, issued on 21 Mar. 1989 is an example of this type system. Other attempts in this area include the U.S. Pat. No. 4,667,158 issued to Robert W. Redlich, issued on 19 May 1987 and to Alec H. Seilly, U.S. Pat. No. 4,350,954 issued on 21 Sep. 1982. There are, however many difficulties with those type devices. Among the difficulties are moisture problems, noise interference, core rotation artifact, and limited linear range.
What is needed is a system which is simple and easy to use, has increased linear range and higher signal to noise ratio which are inherent in a differential variable reluctance transducer. What is also needed are micro power circuitry for use in the system and a telemetry system which will allow the user to count and monitor remote signals from the transducer for ease of evaluation.
It is the object of this invention to teach a differential variable transducer and telemetry system which avoids the disadvantages and limitations, recited above in similar systems. Another object of this invention is to provide an system that is simple to operate, extremely effective and very cost effective with sufficient power and accuracy, at the same time, be extremely efficient.